Generally, a hearing aid is a device which is worn in the ear to supplement hearing ability and is operated to compensate for a user's hearing difficulty by converting an acoustic signal into an electrical signal, by amplifying the electrical signal and by converting the amplified electrical signal into an acoustic signal. As an electroacoustic device for converting an acoustic signal into an electrical signal or converting an electrical signal into an acoustic signal in this way, a microphone and a microspeaker are provided.
FIG. 1 illustrates the construction of a conventional hearing aid. Referring to FIG. 1, a conventional hearing aid includes a microphone 10 for outputting an electrical signal corresponding to a sound wave, a first amplification unit 20 for amplifying a signal output from the microphone 10, an Analog/Digital (A/D) conversion unit 30 for converting the amplified signal into a digital signal, a digital signal processing unit 40 for processing the digital signal output from the A/D conversion unit 30 as a predetermined signal suitable for the wearer of the hearing aid by operating a control program adjusted according to each frequency band for the wearer of the hearing aid, a Digital/Analog (D/A) conversion unit 50 for converting the digital signal output from the digital signal processing unit 40 into an analog signal, a second amplification unit 60 for amplifying the analog signal output from the D/A conversion unit 50, and a microspeaker 70 for outputting the signal amplified by the second amplification unit 60 into an acoustic signal. In the drawing, reference numeral 80, not described, denotes memory and an interface.
Meanwhile, each of the microphone and the microspeaker is provided with a diaphragm for converting an acoustic signal into an electrical signal, or converting an electrical signal into an acoustic signal. Since a conventional diaphragm has a structure having a uniform thickness, and does not satisfy different frequency characteristics for respective persons, the use of the A/D conversion unit for dividing an audible frequency range into a plurality of channels depending on the characteristics of wearers and individually performing amplification and control, the digital signal processing unit for performing a large quantity of computation, the D/A conversion unit, etc. is required, as described above. As a result, there is a problem in that power consumption increases somewhat, so the user of the hearing aid must frequently change the battery thereof.